Sand mulling or conditioning apparatus and plow construction therefor

ABSTRACT

A foundry sand mulling or conditioning apparatus having a cylindrical bowl within which there is provided a novel form of plow construction which, upon peripheral travel around the bowl, functions in a novel manner to elevate the sand and produce a rolling and rotating torus of sand within the bowl.

United States Patent Bisinella 1 May 30, 1972 SAND MULLING OR CONDITIONING References Cited APPARATUS AND PLOW UNITED STATES PATENTS CONSTRUCTION THEREFOR 2,570,223 10/1951 Everett ..259 108 [72] Inventor: Angelo J. Bisinella, Niles, [IL 3,284,059 1 1/1966 Troy. ...259/l07 3,322,404 5/1967 Mcllvame ...24l/l 1O [73] Assignee: Pettibone Corporation, Chicago, Ill. 3,373,974 3/1968 Troy ..259/107 [22] Filed: 1971 Primary ExaminerRobert W. Jenkins 211 App] 110,130 Attorney-Norman H. Gerlach ABSTRACT A foundry sand mulling or conditioning apparatus having a Cl r r 1 1O cylindrical bowl within which there is provided a novel form of [51] Int. Cl. ..B02c 15/00 plow construction which, upon peripheral travel around the [58] Field of Search ..259/ 107, 108, 178, 179, 8; bowl, functions in a novel manner to elevate the sand and 241 /l 10 produce a rolling and rotating torus of sand within the bowl.

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SAND MULLING OR CONDITIONING APPARATUS AND PLOW CONSTRUCTION THEREFOR The present invention relates generally to a sand mulling or conditioning apparatus of the general type which is shown and described in co-pending United States patent application Ser. No. 19,445, filed on Mar. 3, 1970 and entitled SAND MULLING APPARATUS, now US. Pat. No. 3,602,442, granted on Aug. 3 l, 1971 and over which apparatus the present apparatus is an improvement. The invention is particularly concerned with a novel plow construction which is designed for use in connection with a sand mulling or conditioning apparatus of the general type which is disclosed in such patent application and functions in an improved manner to operate upon the sand undergoing treatment or conditioning by the apparatus. I

Briefly, the sand mulling or conditioning apparatus which is shown and described in the aforementioned co-pending patent application embodies a generally cylindrical, cup-shaped receptacle or bowl within which there is mounted for rotation about a vertical axis the usual plow-supporting hub, the latter carrying a series of circumferentially spaced, peripherally mounted, sand-impelling plow constructions, as well as a series of horizontally disposed, similarly spaced and mounted mulling wheels. The function of the plow constructions is to elevate the sand within the bowl into the circular path of movement of the mulling wheels, and the function of the latter is to break up any clusters of sand which may exist at or in the vicinity of the level of the mulling wheels by compacting the sand against the side wall of the bowl. Each plow construction is comprised of two metal plow plates, together with a supporting bracket therefor. The two plow plates, in combination with each other, define three functional sand-engaging surfaces including a first surface which establishes a side plow and is provided on one of the plates, a second surface which establishes a main lift plow and is provided on the other plow plate, and a third surface which establishes a side wing and is likewise provided on the latter plow plate. The first surface operates to direct sand radially outwardly along the bowl bottom and into the path of the second surface. The second surface serves to scoop or lift the sand upwardly into the path of the mulling wheels. The third surface prevents the sand from spilling over the inner side of the second surface. The net result of all three surfaces is to create within the mulling bowl an undulatory elevated rotating and rolling torus of sand which undergoes a continuous kneading action as it rotates and rolls.

The sand mulling or conditioning apparatus of the present invention is similar to the apparatus of the aforementioned copending application and the mulling plow constructions which are associated therewith likewise each presents three functional sand-engaging surfaces which, in a general way, correspond in function to similar surfaces which are associated with each of the plow constructions of said co-pending patent application. However, by reason of certain shape characteristics, relative surface distribution or placement, angular inclination with respect to the bowl side and bottom walls, and size characteristics, an improved mulling action is attained by way of the particular plow constructions of the sand mulling apparatus constituting the present invention, such mulling action including, among other features, a rolling action which is imparted to the torus and results in the latter being caused to follow an undulatory circular path, all in a manner and for a purpose that will be made clear presently.

In addition to the improvement which is effected in the mulling action as stated above, the plow constructions of the present invention are of simplified design, are less costly to manufacture, are easier to assemble and also dismantle for purposes of replacement after becoming worn, and are more rugged and durable than the plow constructions of the aforementioned patent application.

The provision of a mulling apparatus and associated plow constructions such as have briefly been outlined above, and possessing the stated advantages, constitutes the principal object of the present invention. Numerous other objects and advantages of the invention, not at this time enumerated, will readily suggest themselves as the following description ensues.

The invention consists in the several novel features which are hereinafter described and are more particularly described by the claims at the conclusion hereof.

In the accompanying three sheets of drawings forming a part of this specification, one illustrative embodiment of the invention is shown.

In these drawings:

FIG. 1 is a perspective view of the hub of a sand mulling apparatus embodying the present invention, such view showing a plurality of the improved plow constructions operatively applied thereto;

FIG. 2 is an enlarged fragmentary plan view of a peripheral portion of the structure shown in FIG. 1, such view showing the hub and an associated plow construction operatively installed in a mulling bowl;

FIG. 3 is a vertical sectional view taken through a portion of the plow construction and on the line 3-3 of FIG. 2;

FIG. 4 is a reduced vertical sectional view taken through the hub portion of FIG. 1 and on the line 44 of FIG. 1, such view showing the hub portion operatively installed in a mulling apparatus;

FIG. 5 is a reduced vertical sectional view taken substantially on the line 55 of FIG. 2;

FIG. 6 is a vertical sectional view taken substantially on the line 6-6 of FIG. 5;

FIG. 7 is a vertical sectional view taken substantially on the line 77 of FIG. 2;

FIG. 8 is a fragmentary bottom perspective view of one of the plow constructions, showing the same secured in position on the periphery of the hub of the mulling apparatus;

FIG. 9 is an enlarged top perspective view of the plow bracket which is employed in connection with the improved plow constructions;

FIG. 10 is a perspective view of the main lift plow plate which fonns a component part of one of the plow constructions; and

FIG. 11 is a perspective view of the side plow plate which likewise forms a component part of the plow construction.

Referring now to the drawings in detail and in particular to FIGS. 1, 2 and 4, the apparatus which is shown therein constitutes one exemplary form of the invention although not necessarily the commercial embodiment thereof. The apparatus is designed for use in a foundry or similar establishment and serves as a means for mulling and conditioning molding sand preparatory to use thereof in flasks during casting operations. Briefly, the apparatus involves in its general organization a mulling bowl 10 within which there is centrally disposed a rotatable mulling assembly 11 in the form of a central horizontally extending hub 12 on which there are mounted a series of three horizontally disposed mulling wheels 14 and a series of three plow constructions 16, the latter constituting the principal feature of the present invention. Although three mulling wheels 14 and three plow constructions 16 are illustrated in the drawings for exemplary purposes, it will be understood that a greater or lesser number of such wheels and plow constructions may be employed if desired. Regardless of the number of wheels and plow constructions which are employed in any given installation, the circumferential spacing thereof will always be equal with the plow constructions and the wheels alternating as shown in FIG. 1. The mulling wheels 14 are mounted on the periphery of the hub 12 to rotate about vertical axes and, thus, are bodily revolvable about the vertical axis of the hub, as well as being rotatable about their own individual axes. The plow constructions 16 are fixedly secured to the periphery of the hub in a manner that will be described in detail subsequently.

The mulling apparatus further includes an air supply duct 18 for introduction of air under pressure to the interior of the bowl 10 for sand aeration and cooling purposes, a water supply pipe 20 for introducing water into the bowl for admixture with the sand. An electric motor M is operatively connected through a gear reduction device 22 to the rotary mulling assembly 11 and serves, when energized, to drive the latter.

The apparatus is essentially of the batch type and is adapted to mull and condition successive batches of new or previously used molding sand, the batches being periodically introduced into the bowl through the open upper rim thereof by way of an endless, power-driven conveyor or other means (not shown). The bowl is removably supported upon a hollow base casting 24 which, in turn, is mounted on a horizontally elongated, main supporting frame 26. A pivoted damper 27 in the air duct 18 serves to control the flow of air under pressure into the interior of the bowl via the hollow base casting 24 and is operable under the control of an air cylinder 28. The bowl 10 is provided with a substantially flat bottom wall 30 and an upstanding cylindrical side wall 32, the latter being provided with an interior rubber liner 34 and an open circular upper rim 36.

The mulling assembly 1 l is rotatably mounted on a vertical pedestal 40 which is drivingly connected to a vertical shaft 42. The latter carries a gear 43 at its lower end, such gear constituting the output gear of the reduction device 22. A belt and pulley arrangement 44 completes a power drive for the hub from the electric motor M.

The hub 12 may assume various shapes but for exemplary purposes herein, it is shown as having a central upstanding and generally frusto-conical central portion 50, from which there slopes outwardly and downwardly an apron-like portion 52 having the general shape of a paraboloid of revolution. The entire upper surface of the hub is polished to a high degree of smoothness in order to reduce the coefficient of friction between the hub and the sand within the bowl and thus reduce the tendency for the sand to cling to the hub. The contour of the apron-like portion is so designed that the angle of repose of sand particles on any given point thereon will approach a zero angle when the hub is in motion at normal operating speeds.

The mulling wheels 14 are of conventional construction and each is rotatably mounted for free individual rotation on the upper end of a vertically extending supporting arm 54 which projects upwardly from the peripheral region of the hub. The upper surfaces of the wheels are preferably in the form of paraboloids. A solid rubber or other elastomeric tire 56 is carried on the periphery of each mulling wheel 14, the tire being designed for cooperation with the rubber liner 34 of the bowl 10 in effecting the desired mulling action in the usual manner of operation of such mulling wheels.

Considering now the nature of the various plow constructions 16 which constitute the principal feature of the present invention, each plow construction is comprised of three principal parts, namely, two plow plates 60 and 62, and a supporting bracket 64 by means of which the two plow plates are fixedly positioned with respect to each other and also supported from the hub 16. These three cooperating plow construction parts are shown in detail in FIGS. 8 to 11, inclusive.

A single plow construction 16 will now be described, it being understood that all three illustrated plow constructions are the same in design and mode of operation. Referring now to F IGS. 8 and 9, the supporting bracket 64 is in the form of a casting of irregular spider-like design and is provided with three spider arms including a generally rectangular arm 70, a short arm 72 of small proportions, and a long arm 74. The spider arm 70 presents a planar bolting surface 76 and is pro vided with three longitudinally aligned slot-like bolt holes 78. The spider arm 72 presents a bolting surface 79 and is provided with a single threaded bolt hole 80 therein. The spider arm 74 presents a first bolting surface 82 and is provided with two slot-like bolt holes 84 which intersect such surface. It also presents a second bolting surface 86 which is intersected by a single threaded bolt hole 88, and a third bolting surface 90 which extends between the bolting surfaces 82 and 86 and is intersected by two threaded bolt holes 92.

As will be described in greater detail presently, the bolting surface 76 receives thereon the main plow plate 60; and the bolting surfaces 82 and 86 receive thereon the plow plate 62. The bolting surfaces 79 and are coplanar and fit flush against the underneath side of the hub 16 as best illustrated in FIGS. 2, 4, 6 and 7 when the bracket is mounted on the periphery of the hub.

The plow plate 60 constitutes a primary or main plow plate and is shown in detail in FIG. 10. It is in the form of a section of heavy gauge sheet metal stock and is bent as indicated at so as to provide a relatively expansive lift plow section 102 and, in addition, a side wing section 104 which extends at an obtuse angle with respect to the lift plow section 102. The plow plate 62 constitutes a secondary plow plate and is shown in detail in FIG. 11. It is likewise in the form of a section of heavy gauge sheet metal stock and is bent as indicated at 106 so as to provide a relatively wide section 108 and a relatively narrow section 1 10. Said plow plate 62, when considered as a whole and bolted to the long arm 74 of the supporting bracket 64, constitutes a side plow the function of which will be made apparent subsequently.

Attachment of the plow plate 60 to the spider arm 70 of the supporting bracket 64 is effected by means of a series of three threaded studs 112 (see FIGS. 3, 5 and 8) which are welded or otherwise secured to the underneath side of the lift plow section 102, project downwardly through the slot-like bolt holes 78 in the spider arm 70, and are provided at their lower ends with clamping nuts 114 and clamp-type reaction plates 116 constituting components of conventional Nelson bolt assemblies 118. Attachment of the bracket 64 to the periphery of the hub 12 is effected by means of three cap screws 119, one of which extends through a hole in the hub 16 and is threadedly received in the threaded hole 80 in the bolting surface 79 of the short arm 72 and the other two of which extend through holes in the hub 12 and are threadedly received in the threaded holes 92 in the bolting surface 90 of the long arm 74. Attachment of the wide section 108 of the plow plate 62 to the long arm 74 of the supporting bracket 64 is similarly effected by Nelson bolt assemblies 118 which are similar to those previously described and to which similar reference characters have been applied.

Attachment of the narrow section of the plate 62 to the second bolting surface 86 of the long arm 74 of the supporting bracket 64 is effected by a cap screw 1 19a (see FIGS. 1 and 2) which projects through a hole in said narrow section 110 of the plate 62 and is threadedly received in the threaded hole 88 in the bolting surface 86 of the spider arm 74 of the bracket 64.

The positional relationship of the two plow plates 60 and 62 when applied to the bracket 64 and with the latter mounted on the hub 12 within the bowl 10, and the angular relationship of the various plow surfaces which are presented by these plates, are fairly critical factors within certain limits, both as regards their relationship to one another and to the horizontal bowl bottom 30 and the vertical bowl side wall 32. These positional relationships will be described in detail presently when the operation of the mulling apparatus is set forth.

The manner in which the mulling bowl 10 is charged with a batch of molding sand to be mulled and conditioned, the manner in which the sand is mixed with water issuing from the water supply pipe 20 and with air from the duct 18, as well as the manner in which the bowl 10 is emptied of its contents after the mulling or conditioning operation has been completed bear no relation to the operation of the novel plow constructions 16 and, consequently, will not be described herein. For a full understanding of such bowl-charging and bowl-emptying operations, reference may be had to aforem entioned patent application Ser. No. 19,445.

Assuming now that the bowl 10 has been charged with a batch of sand to be mulled and conditioned, that the electric motor M has been energized and that the hub 12 has commenced its rotation in the direction indicated by the arrows in FIG. 2, it will be observed that the plow plate 62 of each plow construction 16 leads the associated plow plate 60 in the direction of rotation of the hub. The narrow section 110 of the plow plate 62 leads the wide section 108 and, as shown in FIG. 2, partially underlies the periphery of the hub 12 while the wide section 108 of the plow plate 62 assumes a position which is generally tangential with respect to the periphery of the hub. These two sections 108 and 110 of the plow plate 62 are inclined inwardly toward the vertical axis of the hub at an angle which is on the order of 45 as indicated in FIG. 7, and the lower edges of both sections lie close to the upper surface of the bottom wall 30 of the bowl 10. When the two plow plates 60 and 62 are bolted in position on the bracket 64, the rear portion 120 of the lower edge of the wide trailing section 108 of the plow plate 62 overlies the front inner portion of the lift plow section 102 of the plow plate 60 as clearly shown in FIG. 2. The function of the plow plate 62 is, therefore, to sweep sand on the bottom of the bowl radially outwardly and with a forward component of movement into the path of the oncoming plow plate 60.

The lift plow section 102 of the plow plate 60 is inclined forwardly and downwardly with respect to the bottom wall 30 of the bowl at an angle which is on the order of 28 as indicated in FIG. 5. It also has a component of inward and downward inclination toward the vertical axis of the hub 12, such inclination being on the order of 10 with respect to the bottom wall 30 as indicated in FIG. 6 and resulting by reason of the particular inclination of the planar bolting surface 76 of the spider arm 70 of the bracket 64. An acute angle exists between the leading edge 122 of the lift plow section 102 of the plow plate 60 and the outside side edge thereof so that such leading edge may be positioned in close proximity to the bottom wall 30 of the bowl l0 and extends generally radially with respect thereto as shown in FIG. 2.

The dihedral angle which obtains at the bend line 100 (see FIGS. 1, 2 and 10) between the lift plow section 102 and the side wing section 104 of the plow plate 60 is on the order of 105 and, thus, since the lift plow section 102 possesses an inward slope of 10, the side wing section 104 possesses an inward slope of approximately 65 with respect to the vertical axis of the hub 12. The various angular relationships set forth above may be varied within certain limits and the net effect thereof is to exert a particular and generally rotary motion to the body of sand within the bowl 10 in a manner and for a purpose that will now be described in detail.

During rotation of the hub 12, the lift plow sections 102 of the plow plates 60 of the plow construction 16 sweep around the peripheral or outer region of the bowl bottom wall 30 and encounter the sand which has been swept radially outwardly and into the path of movement of these lift plow sections. Because the sections 102 are inclined downwardly and forwardly in the direction of rotation of the plow constructions 16, they serve to elevate the sand into the annular area which exists between the side wing sections 104 of the plow plates 60 and the rubber-lined cylindrical side wall 30 of the mulling bowl. It will be noted from an inspection of FIG. 2 that these side wing sections 104, in addition to their inclination with respect to the vertical axis of the hub 12, also bear a secantial relation with respect to the bowl side wall 30 in that their trailing edges are closer to such wall than are their leading edges. The angle involved is on the order of 18. This positional relationship of the side wing sections 104 is such that, in combination with the bowl side wall, there is established, in effect, a series of three revolving funnel structures which crowd the sand toward the bowl side wall and tend to produce a torus of sand which rotates about the vertical axis of the hub while at the same time rolling inwardly of the torus on the circumference of the torus. In addition to this torus motion, an undulatory effect is established due to the spacing between adjacent plow constructions 16. Bearing this particular torus structure of the sand in mind, it will be appreciated that a smearing action on the sand takes place, the side wing sections 104 acting as smearing spatulas and the side wall 30 of the bowl acting as an anvil. In this manner, the formation of sand clusters is inhibited and any clusters which may have an opportunity to form are immediately broken up and uniformly dispersed. The pressure which is exerted upon the torus of sand enhances the desired coating action of the bonding agent which is usually present in the bowl and the net result is that the sand develops greater strength as it rises and recycles from one plow construction to another.

Since the mulling wheels 14 are disposed at an elevation above that of the plow constructions 16 so that the elevated sand is trailed by such wheels, the latter ride through the torus of sand and, by reason of their free rotation, exert a compacting action on the sand by squeezing" the same against the elastomeric liner 34 within the bowl side wall 32.

From the above description, it will be apparent that there has been provided a mulling apparatus which operates upon the sand with increased efficiency over the mulling apparatus of aforementioned co-pending patent application Ser. No. 19,445 in that it establishes the rolling torus action heretofore mentioned and thus affords greater torus agitation. The novel plow constructions which are employed in connection with the present sand mulling apparatus are extremely simple in their design or construction since each consists of only three principal parts and is devoid of structural weldments. Replacement of either the plow plates 60 or the plow plates 62 may readily be accomplished by removing the nuts 114 of the Nelson bolt assemblies 118 and then removing the worn plates and replacing them with new plates on the supporting brackets 64. The elongated or slot-like bolt holes 78 which are formed in the spider arms 70 of the brackets 64 enable slight circumferential adjustment of the positions of the plow plates 60, while the elongated or slot-like bolt holes 84 which are formed in the spider arms 74 of the brackets 64 enable the plow plates 62 to be adjusted circumferentially, as well as enabling them to be tilted upwardly or downwardly with respect to the bowl bottom 30 while the plow plates 62 swing about the axes of the nut and bolt assemblies 118a at the leading ends of the plow plates 62.

The invention is not to be limited to the exact arrangement of parts shown in the accompanying drawings or described in this specification as various changes in the details of construction may be resorted to without departing from the spirit or scope of the invention. For example, the improved plow constructions 16 may be used in a foundry apparatus which does not include rotary mulling wheels and is used primarily for aerating and cooling foundry sand. Only insofar as the invention is particularly pointed out in the accompanying claims is the same to be limited.

Having thus described the invention what I claim as new and desire to secure by letters patent is:

1. A plow construction designed for peripheral attachment to a rotatable hub in a sand conditioning bowl and for revolution within said bowl in one direction about the vertical rotational axis of the hub, said plow construction comprising a plow-supporting bracket having means by which it may be fixedly secured to the hub, said bracket presenting a planar supporting surface which is inclined downwardly and forwardly with respect to the direction of movement of the plow construction, an angular plow plate including a flat lift plow section disposed in face-to-face contact with said inclined supporting surface and a side wing section projecting upwardly from the inner side edge of said lift plow section in the trailing region thereof, and means adapted fixedly and removably to secure said plow plate in position on said planar supporting surface of the bracket.

2. A plow construction as set forth in claim 1 and wherein the securing means for the plow plate includes a plurality of elongated slot-like bolt holes which are fon'ned in the bracket and intersect said planar supporting surface, and cooperating anchoring studs fixedly secured to the underneath side of the lift plow section of the plow plate and projecting through said bolt holes, whereby circumferential adjustment of the plow plate with respect to the bracket may be effected.

3. A plow construction as set forth in claim 1 and wherein the dihedral angle between the lift plow section of the plow plate and the side wing section is on the order of 105.

4. A plow construction as set forth in claim 3 and wherein said planar supporting surface, in addition to its downward and forward inclination, also has a component of inward and downward inclination with respect to the vertical axis of the hub.

5. A plow construction as set forth in claim 1 and wherein said planar supporting surface constitutes a first bolting surface and the bracket is provided with a second bolting surface which is inclined inwardly and upwardly with respect to said vertical axis and is provided with a plurality of elongated slotlike bolt holes in intersecting relation with said second bolting surface, said plow construction comprising, additionally, a second plow plate presenting a planar side plow surface disposed in face-to-face contact with said inclined second bolting surface and secured to the bracket by fastening studs which project through the last mentioned slot-like bolt holes, said last mentioned slot-like bolt holes being inclined out of a horizontal plane.

6. A plow construction as set forth in claim 5 and wherein said planar side plow surface of the second plow plate extends generally in tangential relationship to the periphery of the hub.

7. A plow construction as set forth in claim 6 and wherein said bracket is provided with a third bolting surface and a single bolt hole which intersects said latter bolting surface, the third bolting surface is inclined inwardly and upwardly with respect to said vertical axis, the second plow plate is formed in the medial region thereof with an obtuse angle bend which defines a leading section which projects inwardly on a secantial plane with respect to the periphery of the hub and, in part, underlies the latter, and said leading section is secured to the bracket by a cap-screw which projects into the single bolt hole.

8. A plow construction as set forth in claim 7 and wherein said bracket is of spider-like design, is provided with three generally radial spider arms, the first bolting surface is formed on one of said spider arms, the second and third bolting surfaces are formed on another of said spider arms, said latter spider ann is provided with a fourth bolting surface which is intersected by threaded holes, the third spider arm is provided with a fifth bolting surface which is intersected by a threaded hole, and the means for fixedly securing the bracket to the hub comprises cap screws which extends through holes in the hub and into said threaded holes.

9. A plow construction as set forth in claim 8 and wherein the second plow plate has a trailing section, and the rear portion of the bottom edge of said trailing section is disposed in substantial edge-to-face contact with the upper surface of said flat lift plow section in the leading region of the latter.

Disclaimer 3,666,2 L3.AngeZ0 J. Bz'sz'nella, Niles, I11. SAND MULLING OR CONDI- TIONING APPARATUS AND PLOW CONSTRUCTION THEREFOR. Patent dated May 30, 1972. Disclaimer filed Aug. 3, 1973, by the assignee, Pettz'bone Gowpomtion. Hereby'enters this disclaimer to claims 1, 2, 3, 4, 5, 6, 7, 8 and 9 of said patent.

[Oficial Gazette December 11,1973] 

1. A plow construction designed for peripheral attachment to a rotatable hub in a sand conditioning bowl and for revolution within said bowl in one direction about the vertical rotational axis of the hub, said plow construction comprising a plowsupporting bracket having means by which it may be fixedly secured to the hub, said bracket presenting a planar supporting surface which is inclined downwardly and forwardly with respect to the direction of movement of the plow construction, an angular plow plate including a flat lift plow section disposed in faceto-face contact with said inclined supporting surface and a side wing section projecting upwardly from the inner side edge of said lift plow section in the trailing region thereof, and means adapted fixedly and removably to secure said plow plate in position on said planar supporting surface of the bracket.
 2. A plow construction as set forth in claim 1 and wherein the securing means for the plow plate includes a plurality of elongated slot-like bolt holes which are formed in the bracket and intersect said planar supporting surface, and cooperating anchoring studs fixedly secured to the underneath side of the lift plow section of the plow plate and projecting through said bolt holes, whereby circumferential adjustment of the plow plate with respect to the bracket may be effected.
 3. A plow construction as set forth in claim 1 and wherein the dihedral angle between the lift plow section of the plow plate and the side wing section is on the order of 105*.
 4. A plow construction as set forth in claim 3 and wherein said planar supporting surface, in addition to its downward and forward inclination, also has a component of inward and downward inclination with respect to the vertical axis of the hub.
 5. A plow construction as set forth in claim 1 and wherein said planar supporting surface constitutes a first bolting surface and the bracket is provided with a second bolting surface which is inclined inwardly and upwardly with respect to said vertical axis and is provided with a plurality of elongated slot-like bolt holes in intersecting relation with said second bolting surface, said plow construction comprising, additionally, a second plow plate presenting a planar side plow surface disposed in face-to-face contact with said inclined second bolting surface and secured to the bracket by fastening studs which project through the last mentioned slot-like bolt holes, said last mentioned slot-like bolt holes being inclined out of a horizontal plane.
 6. A plow construction as set forth in claim 5 and wherein said planar side plow surface of the second plow plate extends generally in tangential relationship to the periphery of the hub.
 7. A plow construction as set forth in claim 6 and wherein said bracket is provided with a third bolting surface and a single bolt hole which intersects said latter bolting surface, the third bolting surface is inclined inwardly and upwardly with respect to said vertical axis, the second plow plate is formed in the medial region thereof with an obtuse angle bend which defines a leading sectIon which projects inwardly on a secantial plane with respect to the periphery of the hub and, in part, underlies the latter, and said leading section is secured to the bracket by a cap screw which projects into the single bolt hole.
 8. A plow construction as set forth in claim 7 and wherein said bracket is of spider-like design, is provided with three generally radial spider arms, the first bolting surface is formed on one of said spider arms, the second and third bolting surfaces are formed on another of said spider arms, said latter spider arm is provided with a fourth bolting surface which is intersected by threaded holes, the third spider arm is provided with a fifth bolting surface which is intersected by a threaded hole, and the means for fixedly securing the bracket to the hub comprises cap screws which extends through holes in the hub and into said threaded holes.
 9. A plow construction as set forth in claim 8 and wherein the second plow plate has a trailing section, and the rear portion of the bottom edge of said trailing section is disposed in substantial edge-to-face contact with the upper surface of said flat lift plow section in the leading region of the latter. 